Effects of temperature on the germination, sporulation, and in - vivo infection of Sphaerotheca fuliginea (powdery mildew) on water melon (Citrullus lanathus. L)

Abstract

This research was conducted to investigate the effect of temperature and on the germination, sporulation and in vivo infection of Sphaerotheca fuliginea on healthy water melon. The experiment was laid out in completely Randomized Design (CRD) in the laboratory with 5 replications in each case. Mycelium growth was observed to be highest with 20°C and the control. This was also with 40°C. At 50° however there was no mycelium growth. Significant difference (P<0.05) was observed among the temperature levels on mycelium length with highest length observed at 20°C, but least was at 40°C. Temperature influence on mycelium width had not shown any significant difference (P>0.05). Spores are formed at all temperature levels, with highest spores’ number obtained at 20°C, and least was observed at 50°C. The highest effect of temperature on disease incidence was observed at 20°C (85%) and also at 20ºC, while lowest percentage was at 40°C and 50°C. On the disease severity the highest temperature effect was obtained at 20°C, 30°C, and at optimum temperature 25°C (4, severe infection), while at 40°C was (1, i.e. Mild infection) and at 50°C was observed to be no infection, significant differences (P<0.05) was not shown among the temperature levels on disease severity. Therefore, understanding the optimum ranges of temperature for the development of powdery mildew fungus, May minimized the high rate of infection to occur as well as damages caused on Water Melon.

Key words. Sporulation, In vivo, Spaerotheca fuliginea, Mycelium, Temperature.